IX518, ex-USS Proteus(AS-19), was a submarine tender until she was stricken in Sept 1992. At the time of her first deactivation she was one of the longest serving vessels in the US Navy. She was reactivated as IX518 in 1994 to be used as a berthing ship for overhaul crews at Bremerton, Wash. In 1999 she was stricken again and has been now towed to Esco Marine in the Port of Brownsville. She is here in the scrapping berth on 01 Aug 2007.

Pertinent Details:
Keel laid: September 15, 1941
Launched: November 12, 1942
Commissioned: January 31, 1944
Decommissioned: July 11, 1992
Builder: Moore Shipbuilding and Dry Dock Co., Oakland, Calif.
Propulsion System: Diesel electric (12 diesel engines)
Propellers: two
Length: 574.6 feet (175.1 meters)
Beam: 73 feet (22.3 meters)
Draft: 25.6 feet (7.8 meters)
Displacement: approx. 20,000 tons
Speed: 18 knots
Armament: four 20mm guns
Crew: approx. 1250

Info from Navysite.de
EDIT: Arrived in Port of Brownsville in July 2007